Attin Thomas, Vollmer Doreen, Wiegand Annette, Attin Rengin, Betke Herbert
Department of Operative Dentistry, Preventive Dentistry and Periodontology, University of Göttingen, Germany.
Am J Dent. 2005 Feb;18(1):8-12.
To evaluate the influence of various bleaching systems on subsurface microhardness of enamel and dentin.
60 bovine crowns were distributed among seven groups (A: Opalescence Xtra Boost, B: Opalescence Quick, C: Rapid White, D: Whitestrips, E: Opalescence 10%, F: Opalescence PF 15%). The crowns were sectioned and baseline hardness (Knoop) of enamel and dentin was assessed on the sectioned surface at various distances from the enamel surface. The sectioned surface was covered with wax and the enamel was treated for 10 days with the bleaching agents A-F according to manufacturers' instructions. Bleaching with C-F was conducted each day (C: twice per day for 10 minutes, D: twice per day for 30 minutes, E: 8 hours, F: 4 hours), systems A-B were applied on first and fifth days (A: twice for 10 minutes, B: 1 hour). Finally, hardness was re-assessed. Data were statistically analyzed to compare baseline hardness and final hardness in the respective groups (P< 0.05).
Analysis showed that in Group C, hardness was significantly reduced in both enamel and dentin. In the remaining groups, significant reduction of hardness was observed up to the following depths [microm] in enamel; A: 250, B: 700, D: 300, E: 150, F: 150. In these groups no significant hardness changes were recorded in subsurface dentin.
评估不同漂白系统对牙釉质和牙本质表面下显微硬度的影响。
60颗牛牙冠被分为七组（A组：Opalescence Xtra Boost，B组：Opalescence Quick，C组：Rapid White，D组：Whitestrips，E组：Opalescence 10%，F组：Opalescence PF 15%）。将牙冠切片，并在距牙釉质表面不同距离的切片表面评估牙釉质和牙本质的基线硬度（努氏硬度）。切片表面用蜡覆盖，然后根据制造商的说明，用漂白剂A - F对牙釉质进行10天的处理。C - F组每天进行漂白（C组：每天两次，每次10分钟；D组：每天两次，每次30分钟；E组：8小时；F组：4小时），A - B系统在第一天和第五天使用（A组：两次，每次10分钟；B组：1小时）。最后，重新评估硬度。对数据进行统计分析，以比较各相应组的基线硬度和最终硬度（P < 0.05）。
分析表明，C组的牙釉质和牙本质硬度均显著降低。在其余组中，观察到牙釉质硬度在以下深度（微米）有显著降低；A组：250，B组：700，D组：300，E组：150，F组：150。在这些组中，表面下牙本质的硬度没有记录到显著变化。
